Printing apparatus



Dec. 9, 1952 c. H. GILBERT 2,620,730

PRINTING APPARATUS Filed Feb. 10, 1951 2 SHEETS-Sl-IEET l [MIMJE JHN @@E 2%? A v Moi-222 07 mrlei i 6&[1 er! 5 Dec. 9, 1952 c. H. GILBERT 2,620,730

' PRINTING APPARATUS Filed Feb. 10, 1951 2 SHEETSQSHEET 2 Patented Dec. 9, 1952 UNITED: STATES" PATENT OFFICE Application February 10, 1951, SerialN0. 210,407

This invention. relates, to a.. device .suchas. shownin Patent. 1,801,592,.granted Aprill2l, 1931;. for. printingnames andaddresses-or othenindicia onsales slipsor the like" Heretoioresuch. devicesi have. employed. an 5 inked-typewriter ribbon. for. printing onthe up.- permostsales slip and mechanism for. advancing, the. ribbonbetween successive impressions, and. periodically reversing. the: direction oftravel. Al?" though su-chdevices. have proved .satisfactory-,.the 4 necessary; use ofaha-inking ribbon-:andassociated. winding; mechanism. substantially; increases. the cost .of. manufacture, and. periodically the. inking, ribbon mustbe changed; requiring. anineonvenient andgsomewhat irksome --procedure-.

Therprincipali objects: of the present. invention. are-to provide; asimplifieddeviceewhich dispenses withethe necessity of usinggan .inkingiribbonrandg winding mechanism, but which possesseszallthe:-v advantageous; featuresaof. the prior: devices}. and to provide a. device wherein therinking. member: may--be-.readily-iremoved; andireplaced'.

Another: object; ,is vto provide: 'a-;.relatively: int-1.- expensive inking member whiclris:capablexnot: only of: absorbinga: quantity of:inkx.sufiicient:.to make a substantial.v number; of: impressions: but; also. of releasing ink. in response. to pressure applied during. the printingoperationiin just .sufii'e cientlquantitytoinsurena: clearly .1eg-ible;impres-; sion, and. which, 4 is .capable of withstanding; in? definitely the shocks anmwearu-incident to the. printinggoperation.

For. the.- purposezof. illustration typical Lembodimentssof theeinventionwarer shown :in;the:'accom;-=- panying drawings in which;

Fig.1 isa side. elevation." of at printingg'device constructedv in. accordance? with the presentzina vention, the head. being shown in .raised'position, to receive sales slips:

Fig 2.-is.-an end elevationshowing .the headiin; lowered position with a set of salesislipssinter posed between. the head and-base;-

Fig,., 3 is.an.:enlarged..-top. plan; view of. the: printing. plate;

Fig.4 is an. enlarged side elevation with'the casing removed;

Fig. 5. is an enlargedlongitudinal vertical.- sec=-- tion 7 showing. the. inking. roller. and. associated parts in midi-position;

Fig. 6 is a section on .the. line. 66 ofFig: 5; v

Fig. 7" to. 11'. are enlarged felevations with parts shown'in section of difierenttypesofinking rollers;

Fig: l2is a transverse sectionthroughthe ink. ingroller'shown in Fig. 111,.

The embodiment-herein shown for .theipurpose of illustration comprises a base. 1 formed. at one. endwith an upstanding. block Tto .which. a. plate. holder"4 is rigidly securediin. spaced. relation. to.-

thebase'l sons to permitthe body of'a sales book B to be inserted beneath the plate holder; as'ill'use' tratedin Fig. 2.. The. plate holder is recessedas'i' indicatedlat' 5' (Figs; 5 and'6 andis provided .witha yieldableplate-centering member fi'adaptedito support a printingplate P '(Fig. 3) within the re cess. 5; The printingplateP'maybe of the'con'e struction shown' in Patent'1,9.12',437', grant'ed'J'une 6, 1933, being formedflwithi raisedcharactersin non-reversed order.

l l definingj, a path parallel. tov the planeofl the characters. of the printin ;.plate.P..

Spaceddepending arms20 and 2] are pivoted'j at their upper ends. to aspacer. block...22l (Figs...

4-6) andflthelower endsofthese arms terminate inbifurcated." portions 2 4iand 2 5' aligned :withthe guide. slots l6. and I'll One. endof. a: tension. spring. 2 6. is connected with aspacer. block 28 at therear of. thehousing-and its other end: is cone nectedwithapintfl extending between-the central portions of the arms. 20 and 2l, the:tensionspring 26Lbeing operative .to retract and hold-the armsin vretractedposition.(Fig. 4).. 7

An actuating; member 32' in the form:of=a-.-bell crank is pivotally mounted. between the side. walls Hand. [5 with one arm 33 projecting; outwardly; through an-opening= in the. front of the-casing. 6-- and its. other arm- 34 extendingdnwardly; The. arm 33 is provided. with an operating. handle-36 and .theinner end of the arm 34 is .:pivota1ly.=c'on--- nected by a link.38-with the pin-30, the construction and arrangement of parts .being such rthat'by; depressing the handle. 36 the-arms 20, 2|: are: i swung forwardly and upon releasing the handle the spring 26. retracts thearmsxand restorestha handle to elevated position.

The bifurcated-ends 24-31121257017 the'arms 20" and 2t embrace the end portion of an--.aXleor shaft 40 associated with an ink-carrying I'OHBYQQIT'" ranged to travel alongapath parallel to and sub-- stantially continuous 'with :theplane' of the: char:-

carry disc-like flanged rolls 42 fitting within the slotslE and I l with their. flanges '44 contiguousi-to' the otherfaces of side walls ld' and I5:

Retainers 45 are. riveted or otherwise secured;

to the outer faces of side walls l4 and IE to prevent displacement of the flanged rolls 42 and these retainers are formed with slots corresponding to but slightly smaller than the slots l6 and I1, so as to permit the shaft 40 to be slid outwardly therethrough and the inking roller 4| removed without displacing the flanged rolls 42. With this construction and arrangement, the roller 4| may be quickly removed simply by withdrawing the shaft 40 and replaced by holding the roller aligned with the flanged rolls and then inserting the shaft. As shown in Fig. 6, the lower edges of the retaining plates 45 are turned inwardly to extend under the bearing rollers 42.

Although the use of an inking roller having a removable shaft, as illustrated in Fig. '7, is preferable, various other types of rollers such as illustrated in Figs. 8 to may be used. The roller shown in Fig. 8 consists of a porous inkabsorbent body M formed with integral shafts or hubs 40 The roller of Fig. 9 consists of a solid core 48 formed with ink-receiving grooves 46 and integral hubs 40 and a porous ink-absorbent sheathing 41 providing an ink reservoir of the same type as constituted by the entire roll 4|. This absorbent sheathing 41 should be of substantial thickness, sufiicient to avoid distortion and to insure delivery of ink in substantially the same way as ink roller 4|. As here illustrated, the radial thickness of the sheathing approximates one-third the radius of the roller.

The roller 4l of Fig. 10 is similar to that of Fig. 7, except that in place of the single removable shaft 40 a pair of flanged stub shafts 40 is provided, the inner ends of which terminate in spaced relation with each other to provide an ink-receiving chamber 48 for the reception of a'relatively large free body of ink. The roller 41 of Figs. 11 and 12 is formed with body of porous, ink-absorbent material like the roller 4|, but has a plurality of spaced longitudinal bores 50 defining ink-receiving chambers. The ends of the bores 50 are closed by discs 51 which may be cemented or otherwise secured to the ends of the roller, and a removable shaft 40 slidably fits within the roller and openings in closure plates 5 l.

Regardless of the particular material selected, the roller should be sensibly hard (that is, hard and unyielding to the touch) with a visually smooth and accurately cylindrical peripheral surface-and the peripheral portion, at least, of the roller (whether the roller be of the same material throughout as shown in Fig. 7 or comprise a solid core and ink-absorbent sheeting as shown in Fig. 9) should contain a multitude of minute, generally interconnected cavities forming capillary canals, the majority of those canals which occur close to the peripheral surface of the roller being open at said surface as microscopic pores which are distributed substantially uniformly. The material (which maybe likened to a sponge in internal structure) is capable of taking up and normally retaining a substantial body of ink, thus constituting an ink reservoir of a capacity sufficient for making a plurality of impressions, and of exuding ink from its peripheral surface, when subjected to radial pressure, at a rate proper for making a clear impression. The surface layer of the roller from which the ink exudes and which presses the ink against the paper may for convenience be referred to as the ink delivery element.

When a sales slip is positioned on a printing plate carried by the plate holder, as illustrated in Fig. 2, and the handle 35 is depressed, the inking roller is carried across the upper-most slip or sheet, progressively pressing successive portions of the sheet against the raised characters of the printing plate and simultaneously depositing on the areas corresponding to the raised type a thin film of ink, thus printing on the side of the sheet opposite the printing plate. In this operation pressure is transmitted to the printing roller 4! from the handle through the side walls I4 and 15 of the head, thence from the downwardly facing upper edges of the slots l8 and H to the bearing rollers 42 and thence through the shaft 40 to the printing roller.

The printing action of the inking roller is dependent not only upon its porous ink-absorbent character, but also upon its ability to release a thin film of ink for transfer to the sheet to be printed, thereby insuring a well-inked legible impression, but at the same time avoiding overinking" which would result in blotting or smearing the sheet and consequently rendering the impression more or less illegible. Such a roller, constituting a reservoir capable of holding ink suificient for making at least several hundred impressions, must be capable of withstanding wear or injury which would impair legibility; and as the roller must resist the shocks and strains incident to normal use, it should not only possess a predetermined degree of porosity and ink-absorbency, but also resistance to abrasion and crushing, and a degree of resiliency such as will efiect the desired ink release. In addition, the roller should be of a thermally stable composition, 1. e., a composition which is resistant to cold flow and not thermo-plastic at temperatures of 500 F. and below.

A wide variety of commercially available materials meet or can be treated so as to meet the above requirements, but the most satisfactory are the non-fibrous materials which fall into the following classes:

(a) carbonaceous materials such as carbons, graphites and graphitic materials.

(b) Metals and alloys made of iron, steel, copper, and iron-copper alloys prepared by pressing and sintering the powdered material of various particle sizes in accordance with known principles of powder metallurgy.

(c) Hydrating and chemical cements, including materials composed of Portland cement, concrete, gypsum and silicate cements, with or without a fine aggregate, etc.

(d) Ceramics, including the various porcelainlike materials composed of oxides of-aluminum, silicon and magnesium, as well as clay and shale.

(e) Thermosetting plastics such as phenolformaldehyde and urea-formaldehyde resins with or without fillers.

Inking rollers may be made from such materials by molding to the desired form; or stock bars or tubes may be made from such materials, for example, by casting, molding or extrusion, and inking rollers may be made from these stock bars or tubes by cutting from such bars pieces of the proper lengths to form the rollerturning down the ends to form the integral shafts'when such shafts are employed, and boring the axial journal openings, if necessary, for the reception of separate shafts when such shafts are used. However, in making the rollers, care should be taken to avoid closure ofthe microscopic pores at the peripheral surface of the roller.

The suitability of any selected material will to some extent depend upon the ink to be used, and the selection of the particular type of ink will depend upon the character of the paper or h et-mater a che printed, n. a y: ase the. i z ust e. lativ l e rom volat e i re dients, drying oils, and Y the substantial amounts tr em ntietc. which esult. n kins the sure roller and/orclogging the pores. In the;;ink should 'b e relatively viscous, b,ut

y n semeideer e. of; fluidity, so. hat it neither ow e y-f omairimpreena dxroller nor; resists flow h mmerollen s;subject dto aslight p lonebo twwfl. centinoises to, 10,700: M 20 0.

av. liliov dis isfactory; S0,:1'0ngaaS .theyare free.

rom: the; above-mentioned ingredients.

A proximateanalysis: of-a typical ink (hereinafter referred to as; the, standardink-) which- Lightniineralzoil, e. g:, S;:A. E: or- 20.--- 45:50

Coloring material, predominantly an organic-dye, e. g.-, methyl violet, with or without slight: amounts of ultramarine, oil; soluble resin and lecithin 10-20 The above ink has a viscosity of about. 600 centipoises at Ct Hpyveyer, other inks which were found to be more or less satisfactory, dependinguppnthe; characteristics of, the ink roller, comprise various non-volatile vehicles such as tricresyl phosphate, diglycol laurate, glyceryl mono ric-inoleate, Turkey red oil, and'mixtures of.

these-materials, and'from'10%' to 20 of coloringmaterial composed predominately of a soluble organic dye of high coloring power, such as methyl violet.

Inkingrollers, perferably after formingv to proper-dimension, maybe impregnated with an inkof the above typeby immersing the roller in asuitable container of ink heated-to a temperature of about 150? F. for a period of about one hour, afterwhich the immersed roller is permitted to cool in the ink for a period of at least four hours. The roller is then removed and excess -ink-is wiped off with a cloth.

Qthenmethodsof inking are permissible and in some cases desirable. For example, a highly porous material may be satisfactorily treated simply by immersing the roller in ink at room temperature fora period of about twenty-four hours.- Materials having a low porosity or which, tend'to-repel ink may require vacuum impreg nation either at room or elevated temperatures or a combination fo vacuum and pressure impregnation. Vacuum impregnation may be accomplished in the same manner as above described except that a vacuum is maintained over the ink for about one hour, followedby atmospheric pressure for four hours. Vacuum-pressure impregnation is similarly accomplished, except that a pressure of about 200 lbs. per square inch is substituted for atmospheric pressure in the procedure above otulined. After inking, the impregnated roller-is ready for use in the machine above described.

, A- s -a general;v rule inks-havinga viscosity- When using inks-of the above type and having the specified viscosity range, a satisfactory inking roller should have the folowing basic or es-,

sential characteristics:

(1) Inking factor (the ratio of porosity in per cent multiplied by 10 to the modulus of elasticity in pounds per square inch) of at least two;

(2) Blow pressure (the pressure necessary to force air through approximately 0.29 inch thickness; of. the; impregnated; rollermaterial) -be-.. tween one and one-quarter. and one; hundred.

inchesofmercury;

(4).; Av crushing: strength: of at, least three-e quarter ton; perrsqua-re inch In addition to; these basic; requirement-s; ittisdesirable that. the-inking.- roller should. have the.

following: characteristics (5) Anrink absorption factor, (therfractionof;

theztota-l volumeof the poreswhicn can beefilled.

(6) A: porosity" (percentage of voids to. total:

volume) less than seventy" per: cent;

(7) A pore-factor (theratio of surface porosity in percentzto total porosity-in per cent)-eof= at least oneehalf in the case of' metallic: composi' tions.

It will benoted that'the first-threebasic requirements are interrelated with the desirable:

requirements, and it has been found thatif-an inking roller satisfies theabove four basic requirements, it Will, as a general rule, be satisfactory when used with ink ofthe above type,

although optimum results areobtained if; in addition to observing thebasic requirementsthe remaining requirements aresatisfied.

The porosity of the material'isdefined'as'that' portion of" the total volume, expressed as apercentage; which can be impregnated with alight petroleum oil in the following manner;

(for example-Length=0.854-0;864' Hole diameter=0.l88-0.190" and O. D.=0'.769-0.7'71") and free of any substancewhich will dissolve in the oil, or which will later dissolve in the ink, is first weighed and then immersed in oil in a closed container which is then subjectedto a vacuum, the oil being ata temperature of approximately 70 F. A suitable oilis S. A. E. Grade No. lO-W; Air bubbles will'be liberated from the test piece for several hours, depending upon the particular material. Afterair bubbles cease,and in-no case less than two hours, the-'vacuum-isreleased and the test piece-is allowedto stand submerged in oilv at. atmospheric pressure for--- at-least. eight hours, following-which it is wiped dry with a cloth' and again weighed. The 1 difference in weights before and after impregnation isthe weight of, the oil absorbed, which is thendivided by-the specificgravityof the oil to give thezvolume of oil absorbed.

If the test piece is a regular geometric solid, such as a cylindrical roller, its volume may be calculated with sufiicient accuracy from its dimensions; but, if not, the volume may be determined by observing the loss of weight when the oil-filled test piece is submerged in water. If the test piece contains substances soluble in the ink, they should be extracted with a suitable solvent in a Soxhlet extractor before measuring the porosity factor. In all cases the porosity is expressed as the percentage of the volume of oil absorbed to the volume of the test piece.

The modulus of elasticity is the ratio of stress to strain expressed in pounds per square inch of cross-section and may be'measured as follows.- A test piece, preferably in the form of a cylinder having the above-noted dimensions, is first prepared, care being taken to have the ends ,fiat and parallel and the sides perpendicular to the ends. The cross-sectional area of the test piece is meas- A test-- piece, preferably havingthedimensions of aroller" 7. ured and recorded. Two resistance strain gauges are cemented tothe opposite side portions of the test piece and so oriented that a change in the length of the test piece will cause a change in 8 be filled with ink, and is measured in the following' manner. A roller, preferably having the above-noted dimensions and free from substances which will dissolve in the ink is prepared from electrical resistance of the fine wire grid of the the desired material, and its volume determined strain gauge. The two gauges are connected in by calculation from its dimensions. The porosity series in order to cancel out the efiects of unsymof the material is determined in the manner demetrical loading. Suitable gauges for test pieces scribed above on a second identical sample roller. having the dimensions above noted are Baldwin- The first roller is then inked in the manner above Southward SEE-4, Type A-7 which should be ap- 10 described, after which it is weighed. From the plied in accordance with the manufacturer's ingain in weight of the roller and the known specific struction. The test piece with properly attached gravity of the ink, the volume of ink absorbed gauges is placed in a press testing machine, or and the ink absorption factor may be calculated. other means for applying a steady accurately- The blow pressure is measured as follows: known force and then subjected to compression A roller, pr y having the boved lcading. The value of strain for each of several sions, s first inked n the manner described values of stress is measured by means of a'strain above and is then clamped in a fixture designed indicator calibrated to read strain directly as a to close one end of the vhole and to allow air function of the resistance of the strain gauges pressu e to be introduced into the other end of attached t the t piece From t t th the hole, the ends of the roller being covered by stress/strain diagram may be plotted and the u ber gas ets. The roller and fixture are immodulus of elasticity or stress/ strain ratio obmersed in Clear Water and p u is applied tained. For the purpose of this test, the modulus and gradually inc e sed until a plurality of hllb- I is taken as the stress/strain ratio over the tiles pp On e more P ts O e Surface straight or nearly straight portion of th curve of the roller. The pressure, measured in inches near th origin, of mercury, is then noted and this pressure is The surface roughness is a measurement of considered the blow pressure factor if a further the character of the surface or a specimen of the in r e in pr ure c u u bl to app r at material as determined on the Profilometer using other parts 011 he Surface. the Type J tracer, measurements being made on If the roller is made of a material which conthe surface of a cylindrical roller'along a line tains a gum or other substance soluble in ink, parallel to its axis. This measurement is exthe gum or other such substance must first be pressed in micro-inches, root mean square. The removed by extraction prior to measuring the R M factor is the square of the roughness measblow pressure factor, and the factor so obtained urement, so determined, multiplied by the applies to the case of the unextracted roller as modulus of elasticity in pounds per square inch well as th extracted roller. s above determined, multiplied y 10-11- The surface porosity is defined as the per- The Crushing Strength the e a s its centage of surface area occupied by cavities and compr ssive str n th expressed in pounds p r is determined by microscopic estimation. A recq n and m y be m ur in th f ll w 40 ommended method is to form a test piece having manner- A test p preferably having the a surface which is either flat or only slightly above-noted d s, s a u y p r d in curved so as to be brought into focus in the field h sa ann r as the test piec f r us in of the microscope. A monocular-metallurgical termihing modulus and s then placed in a p microscope having a magnification of 120X and. testing machine or other means of applying a equipped with a recticule in the eye piece havmeasurable compressive force. The load is aping a 5 mm. square, cross ruled into twenty-five plied and gradually increased from zero until 1 mm. squares, is recommended. In estimating the test piece breaks or acquires an appreciable the percentage of voids, each small square in the permanent distortion, at which time the maxireticule is examined and the average of twentymum load sustained is recorded. From this load five estimates is noted. and the area of the test piece the strength in Specific examples of materials representative pounds per square inch can be calculated. of the above classes, together with their above- The ink absorption factor is defined as the fracspecified characteristics, are set forth in the foltlon of the total volume of the pores which can lowing table:

Table Poro ity Modulus Inking Blow di s? RzM Crushing Ink EX Mammal Percent X 10" Factor Pressure Micro- Factor Strength A1381?- ggig,

inch Factor 1 Graphite 19.4 1-7 11 5 0.083 7,000 0,79 d 10.2 1.17 16.5 0 110 0.142 6,000 0, 6

Powder Iron Compac 42. 2 2.0 21.1 4 160 0. 512 13,000 0.72 24 11 2.2 2 55 0.33 13,000 0.50 .7s t 22 is; 2 288 40 f4 3218 is 01358 5: 000 81 75 51 1.3 3 10 0.187 2, 200 0.a 30. s 2. 0 19. 9 3-24 0. 45 4, 300 0.85 46 1.35 3 12 120 0.19 2.600 03 11 0 42.1 0.27 150 5-10 240 0.37 2,500 0.23 Ceramic Composition 30.8 8.13 3. 9 215 3.64 29,000 0.74 13 Thermosetting Resin 43. 0.13 0 -5 310 0.l25 2,300 0 15 4 do 30.2 .4 3 6 210 0.176 1, 580 0,72

Greater than. Less than.

graphite of Example 1 is compressed 121g a'mo're dense material, which is manufactured by U. S. Graphite C0. and sold under the trade name Graphitar #4. The graphite of Example 2 is a commercial electric-furnace graphite may by National Carbon Co. and sold under the trace designation -15.

The powdered iron compact of Example 3 is made from 100 mesh electrolytic iron (Buel 'Metals Co.) with added graphite, ferro-mangan'ese and lubricant, pressed at 4.5 tons per square inch pressure,- sintered and hardened'by quenching. The powdered iron compact of Example 4 was made in a .manner substantially the same as that of Example 3, except that the compact was pressed at 18 tons per square inch pressure.

The powdered copper compact of Example 5 ="was made from 100 mesh copper powder (Metals The gypsum of Example 7 consisted essentially V of calcium sulfate (CaSOQHzO), manufactured by U. S. Gypsum Co. and sold under the trade namedRed Top Plaster of Paris, and was made into a paste with water, cast and then dried. The gypsum of Example 8 was made by the same manufacturer and sold under the trade name Superfine Casting Plaster which was mixed with 60% water by weight, cast and dried. The gy sum'of Example 9 was also made by U. S. Gypsum Co. and sold under the trade name White Hydrocal, which was mixed with 50% water by weight, cast and dried. The gypsum of Example 10 was the same as that of Example 9 but was mixed witih 60% water by weight, cast and dried.

The silicate cement of Example 11 consisted of a conventional mix of sodium silicate, sodium 'fiuosilicate, and fine aggregate, which was made into a paste, then cast and dried. The ceramic material of Example 12 consisted of a magnesium-aluminum silicate, chiefly cordierite crystals, manufactured by American Lava Company and sold under the trade name Alsimag 202.

The thermosetting resin'of Example 13 was a phenol-formaldehyde resin, containing no filler, and was made by Bakelite Corp. and sold under the trade name Bakelite Molding Compound XMQlSl Stiff Flow; and the resin of Example 14 was a similar product containing a dye or pigment and an asbestos filler, and was sold under the trade designation Bakelite Molding Compound BM261 Stiif Flow.

The blow pressure and ink absorptive values in the above table are those obtained when usin the standard ink. As previously noted, these values may vary somewhat, depending upon the satisfactory rollers are of .inorganic, nonfibrous material such as -carbon and graphite, powdered metal compacts, and ceramics such as unglazed porcelain, which are prepared from compressed {powderedmatefial-so that thefinal product has .thefollowing physical characteristics:

inking fac'tor between three and thr'ee 'hundred RZM:factcriess thannve Blow pressure-between three and fifty inches Porosity--between ten and fifty per cent Pore factor-at least three-quarters for metallic compositions Minimum ink absorption factor-fifteen-hundredths Crushing strength-at least one and one-quarter tons per square inch While a freely rotatable roller capable of bodily translation across the surface of the printing plate is desirable and the preferred instrumentality for the purpose, it is to be understood that any equivalent combined ink reservoir and pressure-applying element, for example, a rocker or other form of platen (likewise capable of holding ink for a plurality of impressions and of delivering just sufilcient ink to the paper for each impression, and having physical characteristics equivalent to those of the roller herein specifically illustrated and described) is to be regarded as within the scope of the invention.

By making the roller pores of capillary size the ink does not flow out except in response to pressure of the printing type transmitted through the paper being printed and those areas which are thus compressed yield only enough ink to print legibly and not enough to blur.

By covering the inking roller with a fabric sleeve of closely woven fine thread, the life of the roller is considerably increased, particularly if the roller is made of graphite or other ma-- terial which wears with use. The covering material is preferably woven in the form of a tube having a diameter approximately equal to that of the roller, and each sleeve is then formed by cutting off a length of the tube approximately equal to that of the roller. The tube is woven with the warp extending axially and the weft extending circumferentially and the circumferential threads are preferably formed .of material which shrinks when wet and dried. Thus after the sleeve is slipped over the roller and then wet and dried it grips the roller elastically. However. the sleeve may of course be woven somewhat smaller than the roller so that it must be stretched in slip-ping it over the roller. While the sleeve is shown only at S in Fig. 7, it will be understood of course that it may be used on any of the inking rollers.

Not only must the thread be fine and closely woven but the resulting fabric must be thin; otherwise the printing is not sharply defined. The diameter of the thread should not be greater than approximately one-hundredth of an inch and it is preferably of the order of three to four th'ousandths of an inch. The number of threads per inch should be in the neighbor-hood ofone hundred to two hundred and fifty per inch. While any kind of fine thread may be used, silk, cotton, nylon and rayon, or combinations of these, are preferred. Good results have been secured with warp of /2 (cotton system. of counts) combed Peeler cotton ends per inch and weft of 70/1 (denier) nylon picks per inch. However best results have been obtained with warp of .14/2 (denier) silk approximately 24.0 ends per inch and weft'of 1 4/4 (denier) silk approximately 100 picks to the inch.

.It is to be understood that this disclosure is for the purpose .of illustration and that various changes and modification-s may be made with,- out :departing from the spir t and scope of .L 'inventiomasaset forth in :the appended claims.

In part this :is a continuation .of my iad-pending application Sr. No. 47,785, filed September 4-, 1948.

The claims of companion applications Serial No. 47,785, filed September 4, 1948 (of which this is in part a continuation), and Serial No. 253,143, filed October 25, 1951 (a division of Serial No. 47,785), having been incorporated herein, those applications have been abandoned.

I claim:

'1. A device for printing indicia on a sales slip or the like, comprising two opposed members, one of said members having means for supporting a printing plate having raised characters, and the other of said members having inking means consisting of a porous ink-carrying pressure roller rotatably mounted to move in a path parallel to and substantially contiguous with the raised characters of said plate for progressively pressing successive portions of a sales slip interposed between said opposed members against said plate, the roller comprising hard material whose pores are so fine that ink exudes from the surface of the roller only in response to the pressure of said characters through the sales slip or the like, said material having a crushing strength of at least three-quarters ton per square inch, an R M factor less than five, a blow pressure of between approximately one and one-quarter inches and one hundred inches, and an inking factor exceeding approximately two.

2. An inking roller for printing indicia on a sales slip, comprising a cylindrical member having at least its outer peripheral portion composed of a porous, ink-absorbent, thermally stable material having a crushing strength of at least about three-quarter ton per square inch, an R M factor less than five, a blow pressure of between app-roximately one and one-quarter and one hundred inches, and an inking factor exceeding approximately two.

3. An inking roller as set forth in claim 2, wherein said portion is covered with a fabric sleeve of a closely woven fine thread.

4. An inking roller as set forth in claim 2, wherein said portion is covered with a fabric sleeve, the fabric having a thread count of at least approximately 100 per inch.

5. An inking roller as set forth in claim 2, wherein said portion is covered with a fabric sleeve of a closely woven fine thread, the circumferential threads being stronger than the axial threads.

6. An inking roller as set forth in claim 2, wherein said portion is covered with a fabric sleeve of a closely woven fine thread, the circumferential threads being more elastic than the axial threads. I

7. An inking roller as set forth in claim 2, wherein said portion is covered with a fabric sleeve of a closely woven fine thread, the circumferential threads being of nylon and the axial threads of cellulosic material.

8. An inking roller according to claim 2 further characterized in that the blow pressure of said portion is between three and fifty.

9. An inking roller according to claim 8 further characterized in that the inking factor of said portion is between three and three hundred.

10. An inking roller according to claim 2 further characterized in that the ink absorption factor of said portion is greater than fifteen hundredths.

11. An inking roller according to claim 10 further characterized in that the porosity of said portion is less than seventy per cent.

12. An inking roller for printing indicia on a sales slip, comprising a cylindrical member having at least its outer peripheral portion composed of a porous, ink-absorbent, theremosetting resin having a crushing strength of at least about three-quarters ton per square inch, an R M factor less than approximately 0.176, a blow pressure of between approximately two and six inches, and an inking factor exceeding approximately three.

13. An inking roller for printing indicia on a sales slip, comprising a cylindrical member having at least its outer peripheral portion composed? of a porous ink-absorbent thermosetting resin having a crushing strength of at least three-- quartes ton per square inch, an R M factor less than approximately 0.176, a porosity between approximately thirty and approximately fortythree per cent, a blow pressure between two and six inches, an inking factor between three and three hundred, and a minimum ink absorption factor of fifteen-hundredths.

14. An inking roller for printing indicia on a sales slip, comrising a cylindrical member having at least its outer peripheral portion composed of a phenolformaldehyde resin having a crushing strength of at least 1500 pounds per square inch, an RPM factor less than approximately 0.176, a porosity between approximately 30 and approximately 43 per cent, a blow pressure of at least 2.0, an inking factor greater than 3.0, and an ink absorption factor greater than 0.15.

15. An inking roller for printing indicia on a sales slip, comprising a cylindrical member having at least its outer peripheral portion composed of a porous ink-absorbent, thermally stable, carbonaceous material having a crushing strength of at least about three-quarters ton per square inch, an RPM factor less than five, a blow pressure of between approximately one and one quarter and one hundred inches, and an inking factor exceeding approximately two.

16 An inking roller for printing indicia on a sales slip, comprising a cylindrical member having at least its outer peripheral portion composed of a thermally-stable carbonaceous material having a crushing strength of at least one and onequarter tons per square inch, an R M factor less than five, a porosity between ten and fifty per cent, a blow pressure between three and fifty inches, an inking factor between three and three hundred, and a minimum ink absorption factor of fifteen-hundredths.

17. An inking roller for printing indicia on a sales slip, comprising a cylindrical member having at least its outer periphery portion composed of carbon and having a crushing strength of at least one and one-quarter tons per square inch, an R M factor less than five, a porosity between ten and fifty per cent, a blow pressure between three and fifty inches, an inking factor between three and three hundred, and a minimum ink absorption factor of fifteen-hundredths.

18. An inking roller for printing indicia on a sales slip comprising a cylindrical member having at least its outer peripheral portion composed of graphite and having a crushing strength of at least one and one-quarter tons per square inch, an R M factor less than five, a porosity between ten and fifty per cent, a blow pressure between three and fifty inches, an inking factor between three and three hundred, and a minimum ink absorption factor of fifteen-hundredths.

19. An inking roller for printing indicia on a sales slip, comprising a'cylindrical member having at least its outer peripheral portion composed of graphite having a crushing strength of at least three tons per square inch, an R M factor not exceeding five, a porosity of about twenty per cent, a blow pressure between six and twenty five inches, an inking factor between ten and twenty, and an ink absorption factor between one half and one.

20. An inking roller as set forth in claim 15, wherein the carbonaceous material is covered with a fabric sleeve of a. closely woven fine thread.

21. An inking roller as set forth in claim 15, wherein the carbonaceous material is covered with a fabric sleeve, the fabric having a thread count of at least approximately 100 per inch.

22. An inking roller as set forth in claim 15, wherein the carbonaceous material is covered with a fabric sleeve of a closely woven fine thread, the circumferential threads being stronger than the axial threads.

23. An inking roller as set forth in claim 15, wherein the carbonaceous material is covered with a fabric sleeve of a closely woven fine thread, the circumferential threads being more elastic than the axial threads.

24. An inking roller as set forth in claim 15,

wherein the carbonaceous material is covered with a fabric sleeve of a closely woven fine thread,

the circumferential threads being of nylon and the axial threads of cellulosic material.

25. .An ink roller as set forth in claim 2, further characterized in that said material has a crushing strength of several of tons per square inch.

26. An ink roller according to claim 25, further characterized in that said material is graphite.

27. An ink roller as set forth in claim 25, fur- 14 there characterized in that the inking factor is within the range of three to three hundred and near the lower end thereof.

28. An ink roller as set forth in claim 27, further characterized in that the porosity is within the range of ten to fifty per cent and near the lower end thereof.

29. An ink roller as set forth in claim 28, further characterized in that the ink absorption factor is at least approximate one-half and does not exceed approximately 0.94.

30. An ink roller as set forth in claim 29, further characterized in that the R M factor is at least approximately 0.083.

31. An ink roller according to claim 30, further characterized in that said material is graphite.

CHARLES H. GILBERT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 351,355 Bigelow Oct. 26, 1886 916,357 McCarty Mar. 23, 19 09 1,359,034 Cooper Nov. 16, 1920 1,570,857 Perkins Jan. 26, 1926 1,608,237 Rick Nov. 23, 1926 1,795,480 Dugdale Mar. 10, 1931 2,199,265 Lohrey Apr. 30, 1940 2,262,884 Compton Nov. 18, 1941 2,319,615 Luehrs May 18, 1943 2,319,616 Luehrs May 18, 1943 FOREIGN PATENTS Number Country Date 604,062 Great Britain June 28, 1948 

